This project studies the role of glycogen synthase kinase-3 beta (GSK3B) in modulation of ethanol consumption. GSK3B has been implicated as having an important role in synaptic plasticity and learning. Additionally, GSK3B has been suggested to modulate behaviors for other drugs of abuse. GSK3B has been shown by multiple studies to be inhibited by phosphorylation on residue Ser9 in the medial prefrontal cortex (mPFC) and nucleus accumbens (NAc) of rodents after acute ethanol exposure. However, we recently found that prolonged ethanol consumption causes habituation of this inhibition of GSK3B by acute ethanol in PFC. Our recent studies on rodent drinking behavior show that pharmacological or genetic targeting inhibition of GSK3B in forebrain Camk2a+ neurons will decrease ethanol consumption. However, the mechanisms of GSK3B modulation of ethanol consumption are unknown. This proposal will perform a detailed analysis of ethanol regulation of GSK3B activity, and the specific cellular and neural circuits involved in GSK3B modulation of ethanol consumption. Aim 1 will investigate cellular sites of acute ethanol-induced GSK3B phosphorylation (inhibition) in mPFC and study the time course, duration and mechanisms of chronic ethanol-induced habituation of the acute response to ethanol. Viral vector and Cre-LoxP genetic targeting will be used in Aim 2 to identify whether Camk2a-positive neurons in mPFC are the critical site for GSK3B modulation of ethanol behaviors, and will identify downstream circuits of these neurons. RNAseq studies and bioinformatics in Aim 3 will then study genomic responses downstream of GSK3B following selective deletion or over-expression, thus identifying critical gene networks functioning in GSK3B modulation of ethanol consumption. Finally, Aim 4 will investigate the long-term efficacy and potential end-organ toxicity of Tideglusib, a highly specific inhibitor of GSK3B shown in preliminary studies to decrease ethanol consumption in rodent models. Tideglusib is already approved for phase II clinical trials on disorders such as autism. Together, these studies are highly significant and novel, and will provide needed knowledge regarding the mechanisms of GSK3B modulation of ethanol consumption. This work may also implicate a new agent, tideglusib, for clinical studies on treatment of AUD.